Using implicit solvent simulations, we are able to perform ultra coarse-grained molecular dynamics (MD) simulations of real-size lipid bilayer systems. This approach is designed to circumvent the inherent limitations of all-atom MD simulations in accessing length and time scales that are compatible with scattering experiments. The simulations are found to replicate the behavior of biomimetic lipid bilayer systems used to model structural features of cell membranes. Specifically, we validate the efficacy of this approach in simulating neutron scattering data from unilamellar lipid vesicles with different bilayer rigidities. The simulated vesicle form factors and membrane thickness fluctuations are obtained from calculations that mimic small angle neutron scattering (SANS) and neutron spin echo (NSE) experiments, respectively. Furthermore, the simulation protocol was expanded to domain-forming vesicles and topologically-modulated supported bilayers. Simulations on vesicles are used to evaluate domain stability, size and scattering form factors, as well as the thermal fluctuations in different phase bilayers. Simulations on supported bilayers allow observation of the correlations between domain size, surface curvature, and bending rigidities, providing significant insights into the interplay between these membrane features, including line energy and entropy. These simulations help in interpreting experimental results, and enable an improved molecular understanding at the molecular level.

Ultra coarse-grained molecular dynamics simulations of lipid bilayers

255th National Meeting (2018)

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